As politicians and diplomats struggle for ways to stop violent Arab militia attacks against villagers in the troubled region of Darfur in Sudan, humanitarian aid leaders fear that conditions for millions of displaced Sudanese will only worsen as the country's rainy season approaches.

As Sudan's rainy season draws closer, the threats of famine, disease, and death loom large for two million Sudanese affected by rebel fighting in Western Darfur.

Three humanitarian aid leaders say the 18-month-old conflict has closed off already limited road access to aid workers, disrupting food and medical supplies to people who have fled their village homes to escape armed militia attacks. Some one-point-two million people, more than half who are children under the age of five, are living in cramped, temporary shelters in Darfur or across the border in Chad.

Charles MacCormack, president of the relief organization, Save the Children, told reporters during a news briefing that if enough food, clean water and medicine does not reach the displaced, the rainy season will further complicate this humanitarian crisis.

"There is a real narrowing of the food, medicine and water pipeline that has to be expanded in the coming weeks or things are going to go from bad to worse," he said. "There has already been a doubling of the incidence of hepatitis over the past month and the United Nations estimates that another $255 million is needed to meet these urgent life-and-death needs for food, water and medicine."

Peter Bell, who heads the relief organization, Care, said security and protection for the civilian population also are crucial to resolving the crisis that has forced millions of Sudanese into hiding or into refugee camps.

"There is at least minimal Sudanese police presence, nevertheless, there are still extremely serious problems," Mr. Bell added. "While some of the police are reasonably professional, some have actually been identified by people in the camps as members of the Janjaweed."

For a number of years, farmers have been embroiled in a conflict with Arab nomads over scarce resources. Last year, armed African rebels launched a revolt in Darfur, accusing the government of arming Arab militias called Janjaweed, to loot and destroy African villages.

Mr. Bell called on the international community to pressure the Sudanese government to disarm the Janjaweed militia. He also said hundreds more African Union monitors are needed to help convince people it will be safe to return home to their villages.

George Rupp, the president of the International Rescue Committee, says that will not happen until a better trained, larger security force is put in place.

"Well over one million displaced people are afraid to go back home," he said. "For the most part, these are farmers who have lost their land, their livestock, and any money or valuables that they had. We all agree that the solution that is desirable and necessary is that they go back voluntarily. But they will not do so, unless they are confident of their security."

Human rights organizations say that at least 50,000 people have died since the armed conflict began, among them women and children who have been raped and tortured.